Methods and apparatus employing distribution preserving Tomlinson precoding in transmission of digital data signals

A receiver for receiving a series of signals over a channel, where the signals were first predistorted according to a linear function ##EQU21## and then subjected to ISI of said channel and noise, wherein r.sub.k represents a signal which is to be predistorted according to said linear function, a.sub.i and b.sub.i respectively represent coefficients of first and second polynomials relating to said channel ISI, x.sub.k represents a signal which is subjected to said ISI, and s.sub.k is chosen to cause the signal power of x.sub.k on average to approximately equal the signal power of r.sub.k on average, said receiver comprising:

• a) means for receiving said series of signals and generating from a k'th signal of said series of signals an estimate of r.sub.k -s.sub.k ;
• and
• b) decoder means for generating from said estimate of r.sub.k -s.sub.k and/or an indication of said ISI an estimate of s.sub.k, and from said estimate of r.sub.k -s.sub.k and said estimate of s.sub.k an estimate of r.sub.k.

A method for predistorting telecommunications signals in a coding means of a transmitter prior to transmission over a telecommunications channel, said method comprising:

• a) obtaining telecommunications signals r.sub.k which are to be predistorted;
• and
• b) predistorting said data signals r.sub.k according to a linear function ##EQU28## to provide predistorted output telecommunications signals x.sub.k, wherein a.sub.i and b.sub.i respectively represent coefficients of first and second polynomials relating to the channel impulse response of said telecommunications channel, and s.sub.k is chosen to cause the signal power of x.sub.k on average to approximately equal the signal power of r.sub.k on average.